Does WeatherKit Historical Request work in every country?

Hi! My app, Temp Blanket, uses WeatherKit to provide users with historical high and low temperatures (as well as some weather condition info) for the location from which they wish to request data - they enter the location in a textfield that I then convert to Geo Coordinates before passing on to WeatherKit.

A user in Germany has informed me that her results for Dresden do not match the actual temperatures in the last few days. Actual temperates have been in the -13 to 2 C range and she is seeing a range of 4 to 21 C. In fact, she reports that she gets the same temperatures, no matter what location she tries. When I try Dresden in my app (from my office in Fort Lauderdale, FL) I get correct temperatures for Dresden.

Another data point - If I try to get temperatures for Nairobi, Kenya for the last few days, I get the correct temperatures for yesterday (High of 22C, Low of 16C) but the prior days' temps are very far off. I get temps in the range of -12 to 1 C but the actual temps were 15 to 26 C.

The temperature history data seems to work correctly in the UK, based on feedback from a user there.

So, I have to wonder and ask - does WeatherKit historical data work correctly for all locations worldwide or is it not reliable in certain locations/countries? This is critical information to have so that we do not have dissatisfied users in countries where this service is not yet working correctly. I would disable the app in those countries if this were the case but I need to know what those countries are.

Thanks in advance.